1. Field of Invention
This invention relates to a self-managing storage system for use with data processing and communication systems employing variable length fields that can be nested to any level and more particularly to such a system which provides item level security implemented directly at storage interface and wherein unused storage space can be allocated and reclaimed.
2. Description of the Prior Art
Prior art storage systems have evolved as an array of identical storage cells which were arranged in a rigid manner to accommodate parallel accessing. Parallel data transfer in data processing systems was employed to compensate for the relatively slow speeds of the switching elements employed in the system. Parallel data transfer, in turn, required a fixed width for data or information segments which greatly inhibited the accommodation of variable length fields and nested data structures. As a result, elaborate operating systems and other program mechanisms were created to handle the various data structures and to provide security and protection features. Such program simulation is, of course, relatively slow. Some of these program mechanisms have been implemented in circuitry with some success. However, the result is sitll cumbersome and greater improvement is desired.
Improvements in circuit components, particularly in integrated circuits, have allowed for the decentralization of the various functions in a data processing system. Large scale integrated circuit technology requires regularity and nondedication of specialized or complex functions to circuit chips. Distribution of functions throughout a number of similar or identical integrated circuit chips can accommodate serial data transfer without an undue reduction of throughput in the system. Serial data transfer both accommodates and may be implemented by a number of new storage devices such as charge coupled devices (CCD) magnetic bubble memories and also by improvements in magnetic disk memories which have greatly enhanced access times and storage capacities.
With prior art storage systems, the storage management, except as noted above, was provided by the central processing elements and the input-output controls. By implementing storage management within the storage device, applicational and system software becomes unnecessary for the storage management and can be eliminated. Those particular functions whose control desirably should be placed in the storage unit are the following:
retention of variable-length strings of symbols, up to an implementation-defined maximum; PA1 explicit representation of the beginning and end of strings and the decomposition of strings into substrings; PA1 access of storage strings by means of symbolic names; PA1 storage of strings of information in ordered sets and access to them according to their order; PA1 permission or prohibition of access to strings of information depending upon the identities of the sources of creation of those strings and which sources try to access them; PA1 provision of optional internal representations of strings which optimize access speed by taking advantage of the physical structure of various storage media; and PA1 transmission of strings of information of variable lengths between the storage mechanism and external agencies according to a fixed discipline.
automatic allocation and reclamation of unused storage space as strings of information increase or decrease in size;
When a storage mechanism having the above described functions is applied to communications, word processing, and other less computational uses, a general processing element becomes unneeded in many products.
Since the employment of a serial mode of transmission and storage does not dictate a fixed information segment length or width, this mode of transmission and storage readily accommodates the implementation of the above described functions.
It is, then, an object of the present invention to provide a self-managing storage mechanism that can provide many information handling functions without the requirement of control by a central processing element.
It is another object of the present invention to provide a self-managing storage mechanism that can accommodate variable length data segments that may be nested to any level.
It is still another object of the present invention to provide a self-managing storage mechanism that will in turn provide item level security at the storage interface level.
It is still a further object of the present invention to provide a self-managing storage mechanism that automatically allocates and reclaims unused storage space.